F mazzini



Feb. 3, 1931, F. MAZZINI STRUCTURE OF MONOPLANES WITH THICK WINGS Filed April 4, 1929 2 Sheets-Sheet 1 FRA/Vc IV AZZINI y 5 Affo Feb. 3, 1931. F. MAZZlNl STRUCTURE OF MONOPLANES WITH THICK WINGS Filed April 4, 1929 2 Sheets-Sheet 2 'l I I I \1 Ii'g: l2.

\ sional stresses of the and must have the minimum possible Patented Feb. 3, 1931 PATENT {OF-PICK raAnco MAZZINI, or MILAN, ITALY STRUCTURE OF MONOPLANES FN'ITH THICK WINGS Application filed April 4, 1929, Serial No. 352,465, and in Italy April 13, 1922.

The present invention has reference to improvements in the structure of monoplanes fitted with non-supported wings and more especially in the structure of the wings, the object of the said improvements consisting in simplifying their construction and also in diminishing the weight of the whole by giving the parts which bear the stresses, a shape which is better suited to the work for which they are intended.

It is known that up to the present the monoplanes with nonsustained thick wings, viz: the monoplanes having overhanging wings without external supports, have been constructed in the same way as biplanes, which are fitted with two longrons for each win the two ty es are different, in view of both the di erence in the proportions between the thickness of the wing and its depth, and also of the variability of the said thickness on each section, such thickness betion.

As the resistant or working structure must be inserted within the thickness of the wing weight, it will be convenient to dispose it in such a way as to obtain then'naximum rigidity and resistance of the wing against all bending and torsional stresses to which it is subjected, taking advantage of the particular conditions in which it has to work.

According to the present invention the above object is obtained by placing the sustaining or resistant structure in such a posltion as to allow of the maximum dimensions being assigned to it, and by building it in such a way as to enable it to resist, with the minimum weight consistent with a given coefficient of safety, to all bending and torwing.

Consequently, according to the present invention, the construction with two or more longrons which has been adopted up to now to obtain a resistant structurein the thick wings, is replaced by a single central longron, which is placed approximately along the line passing through the centres of pressure of t e wing, and which is rigid while the structural requirements of mg greatest towards the centre of said sec-.

and resistant in an almost uniform manner and on all-the sides of its contour, both to bending and to torsional stresses.

On the accompanying drawing which serves to schematically illustrate a practical embodiment of the longron and its component parts:

Figs. 1 and 2 show respectively a vertical section through the wing and a plan view of the same.

Fig. 3 is a perspective view of a portion 1 of the longron alone.

Figs. 4 and 5.are cross sections of two tubular forms of the runners of the longron, which are made of sheet metal. 1

Fig. 6 is a cross section of one of the rods of the trellis work. I

Figs. 7 and 8 show in side elevation and in section the details of the connection of the runners with'the rods of the trellis work of the longron.

- Fig. 9 shows in elevation the arrangement of the trellis work on a side face of another embodiment of the longron.

Figs. 10, 11, 12 and 13 show some. types of metallic profile elements which may be used for the construction of the said longron.

In the drawing (Figs. 1 and 2) -a denotes the longron and b the ribs which rest on it. In Fig; 1 the section of the longron a is cross-hatched so as to differentiate its parts from those of the ribs -b which are fastened to it.

As it is shown in the example of the draw ing, the longron is prismatic, has nearly a square section and is composed of four runners c which are disposed along the four edges of the prism, and are conne ted between them on all four faces by a trellis work formed of strips that are disposed four by four and converge in centres which are diagonally opposite, and are joined by diagonal rods earranged inside the -longron (Fig. 3). A three-dimensional net work is thus obtained, which is formed by four runners within which a trellis work is constructed which may be considered as being made up ofa series of tetrahedric equilateral elements having its trellis work rods inclined at an angle of about in relation to the, runners, has the property to resist to torsional stresses with the minimum weight, because,in such case the forces that are acting alongthe oblique rods of the trellis work, balance themselves, and the runners are subjected to prac:

tically no appreciable stress. Said stresses are completely eliminated when the said inclination of the rods is-exactly 45.

Thefour runners are therefore subjected to bending stresses only, while the trellis work is subjected to torsional and shearing stresses, which latter stresses are however absorbed by the torsional stress in the ordinary conditionsof construction.

For the calfilation of the torsional stresses the runners therefore may be considered as being removed, thus remal ing a beam made up of a series of the afore id tetrahedric equilateral elements which resist torsional stresses.

' Although the example of construction illustrated in the drawing refers to a prismatic beam having a square section, it will be understood that it would alsoxbe possible. to use a prism having a polygonal section with any number of sides, but it is always advisable that this section should be a regular polygon, and consequently the runners be at equal intervals and disposed according to the enerating lines of a circular cylindrlcal sur ace and that they should subsequently be trellised so as to constitute an undeformable system.

In the particular case in which the section of the beam is a triangle, the construction of the beam is simplified as in this case there are no inner diagonals, the sole trellis work on the faces being sufficient to render the system undeformable.

With the above said equality of the faces, the uniformity of resistance of the whole contour is obtained, upon which fact the construction according to the present invention is based. Q i

The beam longrons consisting of steel or light alloys, such as duraluminium or electron, can have a tubular shape or can be formed with riveted sheet metal plates, in which case they have preferably a square section as shown in the example in Figs. 4 and 5.

In the first of these figures the runner is made with a simple angle iron -fand with an angle --h having edges lcso bent as to allow of the riveted joints beingm and by a cross section-piece m which serves for riveting these two latter pleces between themselves. The angle piece -f as well as the U section pieces -,-m-

may be provided with one or more recesses Also the trellis work rods may be of a tubular shape or formed of riveted sheetmetal' plates, as shown for instance on Fig. 6, which refers to the case of a runner which is made up with two flat sheet metal plates -p com- Figs. 4, 5 and 6 are indlcated' withthe same, reference letters.

As it is shown in these figures, the runner cis of the same type as the one shown in Fig. 4, the rods -dof the trellis work are fixed to the internal angle iron h by means of the U' boxes gwhich embrace them and to which they are riveted at the point 1*-.; the piece.--g is in turn fixed on the runner by means of the riveted joint On each side of the axis of the juncture of the various elements diaphragms -t, designed to stiffen the section, which are placed within the runners -c and are attached by the bolts u-.

The area of the resisting metallic section of the four runners of the longron is made to gradually decrease from the joint towards the end, and this diminution isobtained by either tapering the angle irons, or by forming them with sheet metal plates superposed in decreasing number or'lastly by composing them of a plurality of jointed stems of different thickness.

The type of longron above described having oblique trellis work rods which converge in diametrically opposite junctures, does not constitute" the only embodiment with which the present invention can be carried into practice, as the central longron may also be formed of a trellis work built up with struts or posts 0 lying on planes which are normal to the axis, and with tie-rods and counter tie rods 'warranged crosswise in trellis work are designed and made in accordance with the usual practice followed for the construction of metallic bridges.

For large aeroplanes, and when extra light metals areused, such as electron, it may also be possible to adopt open and thick angle sections (Figs. 10, 11, 12, 13) both for the runners and for the diagonal pieces, according to the technical practice followed in iron constructions.

The ribs are scarfed into the longron and transmit by flection the forces deriving from the pressure and under-pressure of the air. In normal'fiying, as the longron is situated in correspondence with the line of the centres of pressure, the bending stresses on the two sides balance one another, and in pitching flight a bending moment is transmitted to the longron from the rear side, which is absorbed by the resistance to torsion of the longron.

Having described my invention, what I claim is l. A construction for thick wings on monoplanes comprising a single longron in each wing, said longron being composed of a plurality of tetrahedral elements to create torsional resistance in said longron.

2. A longron for thick wings of monoplanes comprising a pluralty of members arranged to form tetrahedral elements, said tetrahedral elements having one edge in common to create torsional resistance in said longron.

3. A longron for thick wings of monoplanes comprising more than three runners arranged longitudinally in said wing and spaced at intervals corresponding to the vertices of regular polygons and a plurality of members connected between said runners and arranged in tetrahedrons to create rigidity, bending and torsional resistance in said longron.

4. A longron for thick wings of monoplanes comprising more than three runners arranged longitudinally in said wing and spaced at intervals corresponding to the vertices of regular polygons and a plurality of members connected between said runners and arranged in tetrahedrons, adjacent tetrahedrons having one face in common to create rigidity and bending resistance as well as torsional resistance in said longron.

5..A longron for thick Wings of monoplanes comprising four runners arranged longitudinally in said wing and spaced at intervals corresponding to the edges of a rectangular prism, a plurality of rods in zigzag position in each face of said prism and having alternate junctures meeting alternate and making angles of 15 with said surfaces of the square prism.

In testimony whereof I have aflixed my signature this 18th day of March, 1929.

FRANCO MAZZINI.

junctures of rods in adjacent surfaces of the rectangular prism and diagonal rods connecting diagonallyopposite junctures pf said rods. L

6. Alongron for thick wings of monoplan'es comprising four runners arranged longitudinally in said wing and spaced at intervals corresponding to the edges of a square prism, a plurality of rods in zig-zag position in each face of said prism, making angles of 45 with said runners and having alternate junctures in common with alternate juncturcs of rods in adjacent surfaces of the square prism and diagonal rods connecting diagonally opposite junctures of said rods 

